The present invention relates to a non-coherent light source for use in therapy such as photodynamic therapy (PDT), particularly but not exclusively for treating large external surfaces of a patient, and/or a method of use thereof.
Photodynamic therapy involves the administration of a photosensitising drug to an affected area, and its subsequent irradiation with lightxe2x80x94see for example xe2x80x98The Physics of Photodynamic Therapyxe2x80x99 by B C Wilson and M S Patterson, Physics in Medicine and Biology 31 (1986) April No. 4, London GB.
The document WO 97/40888 proposes the use of one or more fluorescent tubes to emit yellow, orange and/or red wavelengths in a lamp for PDT. However, the coefficient of absorption of many PDT drugs for PDT, and of human tissue, is relatively low in these wavelengths, so that the light will have a high penetration depth and is unsuitable for treating superficial conditions. Moreover, the activation efficiency of most PDT drugs is low at these wavelengths and the light intensity available from fluorescent tubes is also comparatively low, which will lead to long treatment times.
The document WO 99/56827 discloses a light source for PDT treatment or diagnosis of the scalp or face, comprising U-shaped fluorescent tubes which emit preferably blue light. This light source would be expensive to manufacture as the U-shaped tubes would have to be manufactured specifically for this application.
According to one aspect of the present invention, there is provided a therapeutic light source comprising a non-planar array of substantially straight fluorescent tubes arranged to emit light substantially within the visible spectrum.
In one embodiment, the array may be mounted on a surface curved perpendicular to the length of the tubes.
In another embodiment, the array may be mounted on at least two planar surfaces set at an angle to one another.
According to another aspect of the present invention, there is provided a therapeutic light source comprising one or more fluorescent grid lamps each comprising a tube having a plurality of folds in the same plane.
According to another aspect of the present invention, there is provided a therapeutic light source comprising a discharge tube and a concave reflector arranged to concentrate light on an area to be treated. In one embodiment, the light source is mounted in a housing having an aperture allowing part of the patient to be located within the housing.
According to another aspect of the present invention, there is provided a light source for PDT including one or more medium/high pressure discharge lamps arranged to emit narrow bandwidth light directly, such that it impinges on a patient with an intensity of at least 3 mW/cm2, preferably between 10 and 100 mW/cm2, and no greater than approximately 200 mW/cm2. Such medium/high pressure discharge lamps can produce a greater intensity than low-pressure fluorescent lamps, while still providing the advantage of narrow bandwidth light over a large area without the need for intervening optics.
Preferably, the bandwidth of the medium/high pressure discharge lamp(s) is 160 nm or less.
Preferably, the arc length of the medium/high pressure discharge lamp(s) is at least 15 mm.
The or each medium/high pressure discharge lamp may be straight or have a folded or serpentine shape.
In either aspect, preferably the one or more lamps are arranged in a housing having a window or aperture through which light impinges on the patient, and preferably a reflector arranged to reflect light specularly or diffusely from the lamps through the window or aperture. The reflector is preferably arranged to provide a uniform output.
The present invention includes a method of use of the light source for PDT, in which a topical photosensitizer such as 5-aminolaevulinic acid (5-ALA) is applied to the affected area of the patient and light from the light source is subsequently applied. Preferably, the method is used to treat superficial oncological or non-oncological conditions. Preferably, the method is used to treat one or more of actinic/solar keratoses, Bowen""s disease, superficial basal cell carcinoma, squamous cell carcinoma, intraepithelial carcinoma, mycosis fungoides, T-cell lymphoma, acne and seborrhoea, psoriasis, eczema, nevus sebaceous, viral infections such as herpes simplex, molluscum contagiosum, warts (recalcitrant, verruca vulgaris or verruca plantaris), alopecia areata or hirsutism. Preferably, the total treatment time is no greater than one hour per session.
The present invention further includes a method of cosmetic or partially cosmetic treatment with a photosensitizing drug for portwine stain removal and hair restoration/removal, and without a photosensitizing drug for skin rejuvenation, wrinkle removal or biostimulation (including wound healing).